AtHKT1 drives adaptation of Arabidopsis thaliana to salinity by reducing floral sodium content

Corresponding author: Dai-Yin Chao (晁代印)

Arabidopsis thaliana high-affinity potassium transporter 1 (AtHKT1; 拟南芥高亲和力钾转运体) limits the root-to-shoot sodium transportation (钠转运) and is believed to be essential for salt tolerance (耐盐性) in A. thaliana. Nevertheless, natural accessions with ‘weak allele’ of AtHKT1, e.g. Tsu-1, are mainly distributed in saline areas (盐碱地区) and are more tolerant to salinity. These findings challenge the role of AtHKT1 in salt tolerance and call into question the involvement of AtHKT1 in salinity adaptation in A. thaliana. Here, we report that AtHKT1 indeed drives natural variation in the salt tolerance of A. thaliana and the coastal (沿海的) AtHKT1, so-called weak allele, is actually hyper-functional in reducing flowers sodium content upon salt stress. Our data showed that AtHKT1 positively contributes to saline adaptation in a linear manner. Forward and reverse genetics analysis established that the single AtHKT1 locus is responsible for the variation in the salinity adaptation between Col-0 and Tsu-1. Reciprocal grafting experiments (相互嫁接试验) revealed that shoot AtHKT1 determines the salt tolerance of Tsu-1, whereas root AtHKT1 primarily drives the salt tolerance of Col-0. Furthermore, evidence indicated that Tsu-1 AtHKT1 is highly expressed in stems and is more effective compared to Col-0 AtHKT1 at limiting sodium flow to the flowers. Such efficient retrieval of sodium to the reproductive organ endows (使...具有) Tsu-1 with stronger fertility (育性) compared to Col-0 upon salt stress, thus improving Tsu-1 adaptation to a coastal environment (沿海环境). To conclude, our data not only confirm the role of AtHKT1 in saline adaptation, but also sheds light on our understanding of the salt tolerance mechanisms in plants.

拟南芥高亲和力钾转运体基因AtHKT1限制了根向芽的钠转运，被认为在拟南芥的耐盐性中发挥作用。然而，带有AtHKT1弱等位基因的自然品种Tsu-1主要分布在盐碱地区，并且表现出较强的耐盐性。这些发现挑战了AtHKT1在耐盐性中的作用，并且质疑AtHKT1基因在拟南芥适应盐环境中所起的作用。本文报道了AtHKT1确实驱动了拟南芥盐耐性的自然变异，沿海的地区的AtHKT1弱等位基因实际上在盐胁迫下减少了花中的钠含量。本文的数据显示AtHKT1基因以线性的方式正向调控了拟南芥对盐的适应性。正向和反向的遗传学试验证明AtHKT1基因是影响Col-0与Tsu-1对于盐适应性不同的主要元素。相互嫁接试验揭示了Tsu-1的芽AtHKT1基因决定了耐盐性，而Col-0的根AtHKT1基因决定了耐盐性。此外，试验证据显示Tsu-1的AtHKT1基因在茎中高表达，并且相比于Col-0的AtHKT1基因更加能够限制通向花的钠流量。这种收回流向花的钠使得在盐胁迫下Tsu-1相比于Col-0具有更高的育性，因此提升了Tsu-1对于沿海环境的适应性。综上，本文不仅证明了AtHKT1基因在盐适应中的作用，同样为植物中耐盐性的研究提供了新的见解。

个人简介：1997.9-2001.7，于安徽大学生命科学学院获得学士学位；2001.9-2007.7，于中科院上海生命科学研究院植物生理生态研究所获得博士学位；2007.7-2011.9，于美国普度大学进行博士后研究；2011.9-2013.4，随普度大学博士后导师转至英国阿伯丁大学继续博士后工作；2013.5-至今，中科院上海生命科学研究院植物生理生态研究所研究员。

doi: https://doi.org/10.1371/journal.pgen.1007086